mame/src/emu/dirom.cpp
2016-08-29 02:02:04 +10:00

83 lines
2.3 KiB
C++

#include "emu.h"
device_rom_interface::device_rom_interface(const machine_config &mconfig, device_t &device, UINT8 addrwidth, endianness_t endian, UINT8 datawidth) :
device_memory_interface(mconfig, device),
m_rom_config("rom", endian, datawidth, addrwidth)
{
}
device_rom_interface::~device_rom_interface()
{
}
const address_space_config *device_rom_interface::memory_space_config(address_spacenum spacenum) const
{
return spacenum ? nullptr : &m_rom_config;
}
void device_rom_interface::set_rom_bank(int bank)
{
if(!m_bank)
emu_fatalerror("%s: device_rom_interface::set_rom_bank called without banking setup", device().tag());
m_cur_bank = bank;
m_bank->set_entry(bank);
}
void device_rom_interface::reset_bank()
{
if(m_bank)
m_bank->set_entry(m_cur_bank);
}
void device_rom_interface::set_rom(const void *base, UINT32 size)
{
UINT32 mend = m_rom_config.addr_width() == 32 ? 0xffffffff : (1 << m_rom_config.addr_width()) - 1;
UINT32 rend = size-1;
UINT32 banks = mend == 0xffffffff ? 1 : (rend+1) / (mend+1);
if(banks < 1)
banks = 1;
if(rend >= mend) {
space().install_read_bank(0, mend, device().tag());
m_bank = device().machine().memory().banks().find(device().tag())->second.get();
m_bank->configure_entries(0, banks, const_cast<void *>(base), mend+1);
m_cur_bank = 0;
} else {
// Round up to the nearest power-of-two-minus-one
UINT32 rmask = rend;
rmask |= rmask >> 1;
rmask |= rmask >> 2;
rmask |= rmask >> 4;
rmask |= rmask >> 8;
rmask |= rmask >> 16;
if(rmask != rend)
space().unmap_read(0, mend);
// Mirror over the high bits. mend and rmask are both
// powers-of-two-minus-one, so the xor works
space().install_rom(0, rend, mend ^ rmask, const_cast<void *>(base));
}
}
void device_rom_interface::interface_pre_start()
{
m_rom_direct = &space().direct();
m_bank = nullptr;
m_cur_bank = -1;
device().save_item(NAME(m_cur_bank));
device().machine().save().register_postload(save_prepost_delegate(FUNC(device_rom_interface::reset_bank), this));
if(!has_configured_map(0)) {
memory_region *reg = device().memregion(DEVICE_SELF);
if(reg)
set_rom(reg->base(), reg->bytes());
else {
UINT32 end = m_rom_config.addr_width() == 32 ? 0xffffffff : (1 << m_rom_config.addr_width()) - 1;
space().unmap_read(0, end);
}
}
}